Modelling the impact of land-cover change on potential soil loss in the Taita Hills,Kenya, between 1987 and 2003 using remote-sensing and geospatial data

In sub-Saharan Africa, natural vegetation is being transformed into agricultural lands at a fast rate, endangering ecosystem services and increasing soil-loss potential, which may trigger land degradation. For the Taita Hills study area in Kenya, multi-temporal land-cover models of 1987, 1999 and 2003, derived from Satellite Pour l'Observation de la Terre (SPOT) imagery using a multi-scale segmentation/object relationship modelling (MSS/ORM) methodology and a rainfall layer, a digital elevation model (DEM) and a digital soil map were applied to model potential soil loss. Population growth in the area has led to a shortage of agricultural land and movement of people to the lowlands, evidenced by a 39% (9.3 km²) increase in croplands from 30% to 41% of the study area during the research time frame. Expansion took place mostly in surrounding foothills and lowlands, at the expense of natural shrubland and grassland, but also occurred in the hills. Universal soil-loss equation (USLE) model results showed a 60% (4 km²) increase in the area of very high potential soil loss, from 7% of the study area in 1987 to 12% in 2003, due mainly to very high soil-loss potential in croplands. Whilst the area of croplands as a whole increased, the relative proportion of very high soil-loss potential in croplands remained 20%, both in 1987 and in 2003, indicating that newly cleared agricultural lands with vulnerable soils are the most at-risk areas.     

Energy-efficient and fault-tolerant drone-BS placement in heterogeneous wireless sensor networks

Wireless Networks - This paper introduces a distributed and energy-aware algorithm, called Minimum Drone Placement (MDP) algorithm, to determine the minimum number of base stations mounted on...     

Applying error correction codes to achieve security and dependability

We apply Linear Error Correction (LEC) code to a novel encoding scheme to assure two fundamental requirements for transmission channels and storage units: security and dependability. Our design has the capacity to adapt itself to different applications and their various characteristics such as availability, error rate, and vulnerabilities. Based on simple logic operations, our scheme affords fast encryption, scalability (dual or more column erasures), and flexibility (LEC encoder employed as a front end to any conventional compression scheme). Performance results are very promising: Experiments on dual erasures outperform conventional compression algorithms including Arithmetic Coding, Huffman, and LZ77.     

Naphtha derived from polyolefins

Conversion of polyolefins (HDPE, LDPE and PP) into feedstock naphtha was investigated by hydroliquefaction process. Hydroliquefaction experiments were carried out under cold hydrogen pressure of 5 MPa at the temperatures between 375 and 450 °C in absence and presence of catalyst. Two types commercial catalysts were used, a hydrocracking catalyst (DHC-8) and a hydrogenation catalyst (HYDROBON). The effect of temperature and catalyst type on product yields and composition of gas and liquid products was investigated. The temperature was the main effect in hydroliquefaction. DHC-8 showed good cracking activity, but it gave the liquid product containing high olefin content same as thermal run. Although HYDROBON catalyst produced the sufficient amount of liquid (and naphtha fraction) at the higher temperature, it gave the liquid product with very low olefin content. The naphtha fractions obtained from polyolefins under the optimal hydrocracking conditions were analyzed by PIONA instrument to determine the hydrocarbon groups. PIONA analysis showed that the naphtha obtained from hydroliquefaction over HYDROBON catalyst could be used as a petrochemical feedstock. However, the naphtha obtained in presence of DHC-8 catalyst, which is to be used a feedstock, was needed further hydrogenation treatment.     

Double Differential Proton and Alpha Emission Cross Sections for Structural Fusion Materials <Superscript>94,95,96</Superscript>Mo

In this study, double differential alpha and proton emission cross sections, which is necessary in determination of heating and damages in structural fusion material research, of ^94,95,96Mo target nuclei have been theoretically calculated by the TALYS 1.8 code at 14.8 MeV neutron incident energy and also compared with available experimental data in EXFOR library. The compound nucleus formation process and pre-equilibrium contribution were found as dominant in the emission of proton and alpha particles, the direct reaction contribution also was seen as dominant in higher particle emission energies.     

Improvement of wood properties by impregnation with macromonomeric initiators (macroinimers)

Scotch pine, eastern spruce, and eastern beech samples sawed longitudinally were impregnated with a new type of polymerization mixture (macroinimer and styrene), leading to crosslinked block copolymers of styrene and poly(ethylene glycol). Weight gains of 36.37–91.13% were obtained after polymerization for 2 h. Water uptake of the polymerized wood was found to be 35.13–72.07% after a water soak test of 144 h. While spruce gave the highest uptake (72.07%), beech showed the lowest value (35.13%). The specimens impregnated with the mixture of macroinimer and styrene showed a water-repellent effectiveness of 35.14–58.15% after a water soaking test of 144 h. The highest values of water-repellent effectiveness were found for spruce, while the lowest values were obtained for pine. A maximum antiswell efficiency (ASE) of 42.43% was obtained for spruce, followed in order by beech and pine, respectively. The ASE value increases with an increase in wt % gain. Improvements of 19.12% in longitudinal compression and 25% in bending strength were also achieved for spruce samples with low weight percent gain. IR spectroscopy was used for chemical characterization of the wood–polymer composite. © 1993 John Wiley & Sons, Inc.     

Comparative study of monoclonal antibody scan in diagnosing orthopaedic infection

When clinical data are insufficient to diagnose infection of bone or joints, nuclear scanning becomes crucial in making an accurate diagnosis. The efficacy of (99m)technetium antigranulocyte monoclonal antibody Fab' fragment (LeukoScan) is prospectively compared with (111)indium white blood cell and (99m)technetium methylene diphosphonate bone scans in 74 patients with suspected musculoskeletal infections. They were grouped according to site of suspected infection: 33 long bones, 23 prosthetic joints, and 18 diabetic feet. Sixty-two of these 74 patients had surgical verification with histopathology or culture. The remaining 12 patients had clinical followup as proof of absence of infection. The overall sensitivity of LeukoScan, (111)indium white blood cell, and (99m)technetium methylene diphosphonate bone scans was 93%, 85% and 92%, respectively. Specificity was 89%, 75% and 52%, and accuracy was 90%, 79% and 74%, respectively. The conclusion from this study is that LeukoScan is more accurate in detecting osteomyelitis, with better sensitivity and specificity in prosthetic joints. Compared with (111)indium white blood cell scans, LeukoScan++ gives superior images, and results are obtained in 1 to 6 hours without biohazard risk from handling blood products.     

Near-field emission from GaAs double-heterostructure laser mirrors

The near fields of GaAs double-heterostructure (DH) laser mirrors are studied both in photoluminescent (PL) excitation and in lasing emission. The various liquid-phase-epitaxial (LPE) layers of the laser diode are optically delineated, withmp0.1-mum resolution, in a wavelength-selective PL detection system. The near fields of the transverse lasing modes are correlated with the LPE layers that constitute the optical waveguide. With special emphasis on the large-cavity fundamental-mode Ppn'N laser, it is found that small changes in refractive index within the waveguide have pronounced effects on the distribution of stimulated power within the LPE layers. The fundamental mode is found to be contained within the slightly higher refractive-index gain region. This explains the previously observed localization of catastrophic mirror damage and the anomalously large angles of beam divergence. High-order modes are also excited in the gain region when its thickness and refractive-index step within the waveguide exceed some prescribed limits.